Increasing abundance of soil fungi is a driver for 15N enrichment in soil profiles along a chronosequence undergoing isostatic rebound in northern Sweden

Wallander, Håkan; Mörth, Carl‐Magnus; Giesler, Reiner

doi:10.1007/s00442-008-1270-0

Cited by 38 publications

(23 citation statements)

References 60 publications

(68 reference statements)

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“…This was an expected outcome of a reduced below ground C allocation to EcM fungi following relief of N limitation to host plants e a pattern similar to that observed along N availability gradients in other high latitude ecosystems (Nilsson et al, 2005;Wallander et al, 2009;H€ ogberg et al, 2010;Wardle et al, 2013). In contrast, P additions significantly increased mycelial ingrowth and marginally increased fungal biomass and no N Â P interactions were observed.…”

Section: Response Of Fungal Biomass and Ingrowthsupporting

confidence: 58%

Decoupled stoichiometric, isotopic, and fungal responses of an ectomycorrhizal black spruce forest to nitrogen and phosphorus additions

Mayor

Mack

Schuur

2015

Soil Biology and Biochemistry

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N Boreal forest Denitrification Ectomycorrhizae Stoichiometry Picea mariana a b s t r a c t Many northern forests are limited by nitrogen (N) availability, slight changes in which can have profound effects on ecosystem function and the activity of ectomycorrhizal (EcM) fungi. Increasing N and phosphorus (P) availability, an analog to accelerated soil organic matter decomposition in a warming climate, could decrease plant dependency on EcM fungi and increase plant productivity as a result of greater carbon use efficiency. However, the impact of altered N and P availability on the growth and activity of EcM fungi in boreal forests remains poorly understood despite recognition of their importance to host plant nutrition and soil carbon sequestration. To address such uncertainty we examined above and belowground ecosystem properties in a boreal black spruce forest following five years of factorial N and P additions. By combining detailed soil, fungal, and plant d 15 N measurements with in situ metrics of fungal biomass, growth, and activity, we found both expected and unexpected patterns. Soil nitrate isotope values became 15 N enriched in response to both N and P additions; fungal biomass was repressed by N yet both biomass and growth were stimulated by P; and, black spruce dependency on EcM derived N increased slightly when N and P were added alone yet significantly declined when added in combination. These findings contradict predictions that N fertilization would increase plant P demands and P fertilization would further exacerbate plant N demands. As a result, the prediction that EcM fungi predictably respond to plant N limitation was not supported. These findings highlight P as an under appreciated mediator of the activity of denitrifying bacteria, EcM fungi, and the dynamics of N cycles in boreal forests.Further, use of d 15 N values from bulk soils, plants, and fungi to understand how EcM systems respond to changing nutrient availabilities will often require additional ecological information.

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Section: Response Of Fungal Biomass and Ingrowthsupporting

confidence: 58%

Decoupled stoichiometric, isotopic, and fungal responses of an ectomycorrhizal black spruce forest to nitrogen and phosphorus additions

Mayor

Mack

Schuur

2015

Soil Biology and Biochemistry

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“…Patterns of soil δ 15 N in depth profiles, now well established [99], [102], result from multiple factors, including: (a) the soil surface can become 15 N depleted as litterfall accumulates at the soil surface while deeper soils can become 15 N enriched due to increased mycorrhizal fungal activity [98]; (b) N loss from nitrification and denitrification can result in either: (i) a steady soil 15 N enrichment with depth given abundant N availability [98]; or (ii) enriched soil 15 N at intermediate depth in arbuscular mycorrhizal (AM) systems and/or sites of higher available nitrogen [103]; and/or (c) increases in soil fungi with depth resulting in soil 15 N enrichment [104]. Differences in soil texture may also play a role in defining soil δ 15 N, with increasing clay % generally accompanying soil 15 N enrichment [105], as well as land use intensity altering soil δ 15 N [106].…”

Section: Discussionmentioning

confidence: 99%

Integrating Stand and Soil Properties to Understand Foliar Nutrient Dynamics during Forest Succession Following Slash-and-Burn Agriculture in the Bolivian Amazon

Broadbent¹,

Zambrano²,

Asner³

et al. 2014

PLoS ONE

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Secondary forests cover large areas of the tropics and play an important role in the global carbon cycle. During secondary forest succession, simultaneous changes occur among stand structural attributes, soil properties, and species composition. Most studies classify tree species into categories based on their regeneration requirements. We use a high-resolution secondary forest chronosequence to assign trees to a continuous gradient in species successional status assigned according to their distribution across the chronosequence. Species successional status, not stand age or differences in stand structure or soil properties, was found to be the best predictor of leaf trait variation. Foliar δ13C had a significant positive relationship with species successional status, indicating changes in foliar physiology related to growth and competitive strategy, but was not correlated with stand age, whereas soil δ13C dynamics were largely constrained by plant species composition. Foliar δ15N had a significant negative correlation with both stand age and species successional status, – most likely resulting from a large initial biomass-burning enrichment in soil 15N and 13C and not closure of the nitrogen cycle. Foliar %C was neither correlated with stand age nor species successional status but was found to display significant phylogenetic signal. Results from this study are relevant to understanding the dynamics of tree species growth and competition during forest succession and highlight possibilities of, and potentially confounding signals affecting, the utility of leaf traits to understand community and species dynamics during secondary forest succession.

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“…Transfer of 15 N‐depleted N to ectomycorrhizal plants and retention of 15 N‐enriched N by ectomycorrhizal fungi appears to drive 15 N depletion in surficial litter layers and 15 N enrichment in deeper soil horizons, as also suggested in several previous studies (Högberg et al ., ; Billings & Richter, ; Lindahl et al ., ; Hobbie & Ouimette, ). For example, in chronosequences of boreal forests the lowest part of the surficial organic mor layer becomes increasingly enriched in 15 N with age (Wallander et al ., ). In these systems, correlations of 15 N with fungal biomass and low pH (limiting nitrification) led the authors to conclude that redistribution of N isotopes resulted from the ectomycorrhizal symbiosis rather than from N losses.…”

Section: Patterns Of Soil δ15nmentioning

confidence: 97%

Nitrogen isotopes link mycorrhizal fungi and plants to nitrogen dynamics

2012

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Contents Summary367I.Introduction367II.Background on isotopes368III.Patterns of soil δ15N370IV.Patterns of fungal δ15N372V.Biochemical basis for the influence of fungi on δ15N patterns in plant–soil systems373VI.Patterns of δ15N in plant and fungal culture studies374VII.Mycoheterotrophic and parasitic plants375VIII.Patterns of foliar δ15N in autotrophic plants376IX.Controls over plant δ15N377X.Conclusions and research needs378Acknowledgements379References379 Summary In this review, we synthesize field and culture studies of the 15N/14N (expressed as δ15N) of autotrophic plants, mycoheterotrophic plants, parasitic plants, soil, and mycorrhizal fungi to assess the major controls of isotopic patterns. One major control for plants and fungi is the partitioning of nitrogen (N) into either 15N‐depleted chitin, ammonia, or transfer compounds or 15N‐enriched proteinaceous N. For example, parasitic plants and autotrophic hosts are similar in δ15N (with no partitioning between chitin and protein), mycoheterotrophic plants are higher in δ15N than their fungal hosts, presumably with preferential assimilation of fungal protein, and autotrophic, mycorrhizal plants are lower in 15N than their fungal symbionts, with saprotrophic fungi intermediate, because mycorrhizal fungi transfer 15N‐depleted ammonia or amino acids to plants. Similarly, nodules of N2‐fixing bacteria transferring ammonia are often higher in δ15N than their plant hosts. N losses via denitrification greatly influence bulk soil δ15N, whereas δ15N patterns within soil profiles are influenced both by vertical patterns of N losses and by N transfers within the soil–plant system. Climate correlates poorly with soil δ15N; climate may primarily influence δ15N patterns in soils and plants by determining the primary loss mechanisms and which types of mycorrhizal fungi and associated vegetation dominate across climatic gradients.

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Increasing abundance of soil fungi is a driver for 15N enrichment in soil profiles along a chronosequence undergoing isostatic rebound in northern Sweden

Cited by 38 publications

References 60 publications

Decoupled stoichiometric, isotopic, and fungal responses of an ectomycorrhizal black spruce forest to nitrogen and phosphorus additions

Decoupled stoichiometric, isotopic, and fungal responses of an ectomycorrhizal black spruce forest to nitrogen and phosphorus additions

Integrating Stand and Soil Properties to Understand Foliar Nutrient Dynamics during Forest Succession Following Slash-and-Burn Agriculture in the Bolivian Amazon

Nitrogen isotopes link mycorrhizal fungi and plants to nitrogen dynamics

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